Probiotics Tested in Marathon Runners

Guest BloggerMicrobiome Environment

healthy people

Tales of gut woes for long-distance runners are well-documented.

Runners sometimes cross a finish line only to vomit or collapse onto a stretcher. The usual reason? Excess heat—caused either by outside temperatures or the metabolic fire within—stresses the body, blunting performance. Heat-stressed athletes often endure what is termed “leaky gut”, a condition where the intestinal lining becomes more permeable, allowing infections to take hold.

Leaky gut effects
  • infections like cold and flu
  • increased inflammation
  • diarrhea, nausea and vomiting
  • slowed tissue repair
  • performance suffers
Probiotics may be useful in leaky gut

In one study, 141 marathon runners were recruited for a randomized, double-blind intervention study during which they received a strain of Lactobacillus rhamnosus or placebo for a three-month training period. At the end of the training period the subjects took part in a marathon race. The probiotic  appeared to shorten the duration of GI-symptom episodes.

And in a newer study, researchers in the UK wondered whether probiotics may alleviate some of that distress. Four weeks of probiotic supplementation reduces GI symptoms during a marathon race appeared in European Journal of Applied Physiology in April of 2019.

The study was comprised of 24 runners who were randomly assigned to a probiotic or a placebo group. The probiotic group received daily supplements of strains of lactobacillus acidophilus,  bifidobacterium bifidum , and bifidobacterium animalis subs p. lactis for 28 days before a marathon race event.

GI symptoms (during supplement period and the race) as well as serum lactulose: rhamnose ratio and other biomarkers were recorded.

The results were encouraging. GI symptoms were lower during the 3rd and 4th weeks of the supplement period compared to the 1st and 2nd weeks in probiotic group. The placebo group reported no such change. In addition, GI symptom severity during the final third of race was lower in probiotic group. Alas, the ultimate preferential outcome in performance times were not affected though speeds during the race relative to symptom severity were.

The authors concluded:

“Probiotics supplementation was associated with a lower incidence and severity of GI symptoms in marathon runners, although the exact mechanisms are yet to be elucidated. Reducing GI symptoms during marathon running may help maintain running pace during the latter stages of racing.”